1. Field of the Invention
The present invention relates to dental treatment equipment and root canal dental instruments. Specifically, it relates to a self-contained root canal dental instrument that combines the operations of a root canal spreader, a root canal condenser, and a root canal filling material heater.
2. Description of the Background
A need has existed for a long time for a way to reduce the time involved in filling a prepared root canal of a human tooth with the filling material. The time involved being used in the continual pick up of separate dental tools for spreading filling material, condensing the filling material, and the alternate heating and reheating of the filling material, during the spreading and condensing operations. Equally important is the complete adaptation of the filling material to secure a hermetic seal against leakage.
Gutta percha is the usual material that is used for filling root canals. Gutta percha, as with other root canal filling materials, must be spread and condensed in the root canal and heated to improve its flow and adaptation qualities. Gutta percha material deforms when warmed and compressed. It becomes pliable at 25 to 30 degrees Celsius, it becomes soft at 60 degrees Celsius, and it decomposes at 100 degrees Celsius. At such temperatures a phase transition occurs allowing the gutta percha to flow into the many irregularities of the prepared root canal, thus allowing for a three-dimensional obturation and sealing to occur. Such a three-dimensional obturation and sealing is necessary for success in root canal therapy.
When the filling material is softened, it is then compressed into the numerous aberrations of the root canal in order to effectively seal the root canal cavity. The compressing of the filling material in the prior art is performed by using root canal filling spreaders and filling condensers of a variety of sizes and with several handle designs (both long and short). The root canal filling spreaders and filling condensers deform the filling material under heat and stress and allow compaction and condensation that leads to the lateral spreading to fill the voids in the root canal. As bits or points of filling material are placed into the root canal, as hereinbefore described, the heated, spreader tool is forced between the bits or points of material after each such insertion which pushes and compacts the filling material vertically to the apex of the root canal and, concurrently, laterally. The tool is pressed manually and also rotated side to side to achieve the spreading of the material. It also acts as a heat sink cooling down quickly for controlled concentration.
The filling spreaders and condensers of the prior art for root canal work are generally of stainless steel or chromium plated brass. The filling spreaders are smooth, flat ended and slightly tapered. For the most part, the prior root canal filling spreaders and condensers had to be heated over a flame, such as over the flame of a Bunsen burner, and then passed into the mouth of a dental patient and then into the prepared root canal where the filling material has been placed. Such tools had to be transported quickly from the Bunsen burner into the mouth of the patient and into the tooth and the root canal and against the cold mass of filling material. There is the constant danger of burning the patient about the mouth each time a heated dental tool is moved from the flame to inside the mouth. Moreover, if it becomes too hot the filling material will stick to the dental tools of the prior art.
A few prior art attempts have been made to provide for heating the tools while in the mouth. However, problems have been encountered. For example, the tips have been bulky and too wide. Also, the tips do not wedge lock into place and 360 degree rotation has been encountered which reduces the effectiveness of the condensing operation. Further, the heat control has been unreliable, the system having as many as ten dial settings which required an assistant or required the dentist to stop the condensing operations to attempt to make a better heat selection or to interrupt the heat process. In addition to the above problems, the filling material sticks to the surface of the so called heat control tools, and the system has a cumbersome power box and control means.
U.S. Pat. No. 4,392,827 issued Jul. 12, 1983 to the inventor herein proposes a solution in the form of a self-contained dental instrument inclusive of a combination spreader, condenser, and a filling material heating unit, each of which is alternately and/or concurrently useable while inserted within the root canal structure of a patient. The '827 invention generally includes a plugger component or "tip" which combines the functions of a spreader, a condenser, and a material heating unit; a handle component affixed to the plugger component; a power supply component for producing heat; and a transmission component for transmitting heat produced by the power supply component to the material heating unit of the plugger component. The transmission component has a conveniently located finger operation switch to interrupt the power supply and cut off the flow of heat. A variety of plugger components are provided in a range of sizes to fit the range of internal sizes in different parts of the root canal. The '827 invention reduces the number of entries into the mouth that are necessary during a root canal filling, and also provides for inducing the heat for the tool after the tool is in the tooth at the root canal cavity. The plugger unit or tip is used to heat the filling material and then laterally condense or press the filling material into the root canal areas. Thereafter, the tip may also be used to maintain the heat or reheat the filling material and to vertically condense the filling material into the root canal in a compacting type of operation. While the use of the filling condenser to vertically condense the filling material is often referred to as a plugging operation, the use of the filling spreader to laterally condense the material before the vertical condensing is is also a part of the total plugging operation. Additional bits or points of filling material are placed into the root canal cavity and then followed by the spreading and condensing operations described hereinbefore for the filling spreader and condenser root canal tools. These operations are continued until the required amount of filling material plugs and seals the root canal in accordance with dental art.
The above-described invention eliminates the risk and expense of the many repeated tool exchanges and reheating operations. However, the device itself has proven expensive. The '827 device made use of a tip which housed both heating element and resistor. The presence of the resistor within the tip increased the cost. More significantly, the tip could not be sterilized due to the resistor.
It would be greatly advantageous to provide a modified design in which the resistor is moved out of the tip and into the hand piece, along with other design modifications, to thereby make the instrument more cost effective for the dentist and sterilizable for infection control requirements.